Why are my fish staying up at the top of the tank?

Answer by  SunnyStars (836)

It could be because of any amount of nitrites or ammonia. Also because of high nitrates, sickness, poison or something else. Change 25% - 75% of the water. Replace the water with new, safe, dechlorinated water. Test the water using a water quality test kit at least once a week.

Answer by  raun08 (1839)

Presuming they aren't doing so with their bellies up, it sounds like you have low oxygen levels in your water. Getting an aerator of some kind will help. It's also possible one of the bigger/more aggressive fish has claimed the bottom of the tank as 'theirs'.

Answer by  1magicturtle (51)

Your fish may be lacking oxygen. Immediately place an airstone or suitable filter system to encourage oxygen in the tank.